Power delivery system and method

ABSTRACT

A power delivery system includes a first inverter, a second inverter, and a turbocharger assist device. The first inverter is electrically connected to a primary bus and configured to receive electric current from an alternator via the primary bus to supply the electric current to a first load. The alternator generates the electric current based on mechanical energy received from an engine. The second inverter is electrically connected to a secondary bus discrete from the primary bus. The turbocharger assist device is mechanically connected to a turbocharger operably coupled to the engine. The turbocharger assist device is electrically connected to the secondary bus and configured to generate electric current based on rotation of a rotor of the turbocharger. The second inverter is configured to receive the electric current generated by the turbocharger assist device via the secondary bus to supply the electric current to a second load.

BACKGROUND Technical Field

The inventive subject matter described herein relates to turbochargedengines.

Discussion of Art

The amount of power produced by a cylinder in an engine depends on aquantity of fuel burned in the cylinder and an amount of air in thecylinder. The power can be increased by providing additional air intothe cylinder. Turbochargers are used to increase the amount of airintroduced into each cylinder by compressing the air prior to enteringthe cylinders. Exhaust gas from the engine typically drives theturbocharger by rotating a turbine of the turbocharger. The turbine isconnected to a compressor such that the rotating turbine drives rotationof the compressor to increase the pressure of the air directed to thecylinders.

Turbochargers can be difficult to control because the rotating speeds ofthe turbine and compressor may be based on properties of the exhaust gasfrom the engine, such as pressure, flow rate, temperature, and the like.Fluctuations in exhaust gas pressure can cause variations in the speedof the turbocharger, which can have detrimental effects. For example,the turbocharger may surge, which can damage the turbocharger machinery.To address surge and other issues, some turbochargers may be fitted withsystems to limit turbocharger speed, such as blow off valves, but thesesystems often result in reduced compressor efficiency. It may bedesirable to have a turbocharger-containing power delivery system thatdiffers from the turbocharger control systems that are currentlyavailable.

BRIEF DESCRIPTION

In one or more embodiments, a power delivery system is provided thatincludes a first inverter, a second inverter, and a turbocharger assistdevice. The first inverter is electrically connected to a primary busand configured to receive electric current from an alternator via theprimary bus to supply the electric current to a first load. Thealternator generates the electric current based on mechanical energyreceived from an engine. The second inverter is electrically connectedto a secondary bus that is discrete from the primary bus. Theturbocharger assist device is mechanically connected to a turbochargeroperably coupled to the engine. The turbocharger assist device iselectrically connected to the secondary bus and configured to generateelectric current based on rotation of a rotor of the turbocharger. Thesecond inverter is configured to receive the electric current generatedby the turbocharger assist device via the secondary bus to supply theelectric current to a second load.

In one or more embodiments, a method (e.g., for delivering power) isprovided that includes supplying electric current from an alternator toa first inverter via a primary bus of a power delivery system for thefirst inverter to supply the electric current to a first load. Thealternator generates the electric current based on mechanical energyreceived from an engine. The method also includes supplying electriccurrent from a turbocharger assist device to a second inverter via asecondary bus of the power delivery system for the second inverter tosupply the electric current to a second load. The secondary bus isdiscrete from the primary bus. The turbocharger assist device ismechanically connected to a turbocharger that is operably coupled to theengine. The turbocharger assist device is configured to generateelectric current based on rotation of a rotor of the turbocharger.

In one or more embodiments, a vehicle propulsion system is provided thatincludes an alternator, a turbocharger, a turbocharger assist device,first and second traction motors, a first inverter, and a secondinverter. The alternator is configured to generate electric currentbased on mechanical energy received from an engine. The turbocharger isoperably coupled to the engine. The turbocharger assist device ismechanically connected to the turbocharger and configured to generateelectric current based on rotation of a rotor of the turbocharger. Thefirst and second traction motors are mechanically connected to first andsecond wheelsets, respectively. Each of the first and second wheelsetsincludes at least two wheels. The first traction motor is electricallyisolated from the second traction motor. The first inverter iselectrically connected to the first traction motor and to the alternatorvia a primary bus. The first inverter is configured to receive theelectric current generated by the alternator to power the first tractionmotor to rotate the wheels of the first wheelset for propelling movementof the vehicle. The second inverter is electrically connected to thesecond traction motor and to the turbocharger assist device via asecondary bus. The second inverter is configured to receive the electriccurrent generated by the turbocharger assist device to power the secondtraction motor to rotate the wheels of the second wheelset forpropelling the movement of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made briefly to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a turbocharged power system accordingto an embodiment;

FIG. 2 is a schematic circuit diagram of a power delivery systemaccording to an embodiment;

FIG. 3 illustrates a vehicle representing an example application of thepower delivery system shown in FIG. 2;

FIG. 4 is a graph depicting a control protocol for controlling a supplyof electric current to a load according to an embodiment; and

FIG. 5 is a flow chart of a method for delivering power from aturbocharged engine according to an embodiment.

DETAILED DESCRIPTION

One or more embodiments described herein provide systems and methods forcontrolling, supporting, and using a turbocharger that is operablycoupled to an engine. For example, the systems and methods describedherein include a turbocharger assist device that is mechanicallyconnected to the turbocharger. The turbocharger assist device is anelectromechanical device that can be used as a motor and a generator.The turbocharger assist device is electrically connected to a load, andin embodiments of the present disclosure the rotation of one or both ofthe rotors (e.g., the turbine and compressor) of the turbocharger isused by the turbocharger assist device to generate electric current thatis supplied to power the load. At least one technical effect of thesystems and methods described herein is energy-efficient operationbecause the electric current generated by the turbocharger assist deviceto power the load is based on energy that is salvaged or recycled fromengine exhaust gases which rotate the rotors of the turbocharger. In anon-limiting example, the load connected to the turbocharger assistdevice is a traction motor on a vehicle such that the energy salvagedfrom the engine exhaust gas is converted to electric current used topower the traction motor to propel the vehicle.

FIG. 1 is a schematic diagram of a turbocharged power system 10according to an embodiment. The turbocharged power system includes anengine 14 and a turbocharger 12 operably coupled to the engine. Theturbocharger is operably coupled to the engine because the exhaust gasfrom the engine is drives a turbine rotor 26 (referred to herein asturbine) of the turbocharger, which in turn rotates a compressor rotor24 (referred to herein as compressor) of the turbocharger to compressair that is fed to the engine for combustion with fuel within enginecylinders. The turbocharger is a forced induction device that compressesthe air to force an addition amount of air into the cylinders of theengine relative to naturally-aspirated engines. The additional airenables the injection of additional fuel for combustions, so theturbocharger effectively increases the power from each combustion cyclein the cylinder of the engine. In a non-limiting example, theturbocharged power system may be a vehicle propulsion system that isdisposed onboard a vehicle and generates tractive force for propellingthe vehicle.

The engine has a drive shaft 16 mechanically connected to an alternatoror generator 18. Unless otherwise specified, the term “alternator”includes generators and any other device that is configured to convertmechanical energy to electrical energy (e.g., power) through therelative rotation of conductors in a magnetic field, such as a rotor andstator assembly. The alternator generates electrical energy (e.g.,electric current) based on the rotation of the drive shaft, and thecurrent is supplied to one or more loads 22. In the non-limiting examplein which the turbocharged power system is installed on a vehicle, theone or more loads may include one or more traction motors for propellingthe vehicle and/or one or more auxiliary devices, such as fans, airconditioners, lights, power supply devices, compressors, pumps, or thelike. The alternator is coupled to power control circuitry 20 whichcontrols the conduction of current to the one or more loads. The powercontrol circuitry may include rectifiers, switches, inverters,converters, capacitors, and/or the like. The power control circuitry iscontrolled to mediate the source of electric current to the loads atdifferent times, the amount of current supplied to the loads, thedirection of current (e.g., to the loads or from the loads), and thelike.

The compressor of the turbocharger is operable to provide a supply ofcompressed air to an intake manifold 28 for combustion in the engine.The turbocharger is mechanically connected, for example, by bolting, toan exhaust manifold 30 of the engine. The turbine of the turbocharger isfluidly coupled to the exhaust manifold such that the exhaust gases 34of the engine are directed to flow through the turbine. The turbineextracts energy from the exhaust gases of the engine which spins theturbine. The turbine is mechanically connected to the compressor via aturbocharger shaft 32. The rotation of the turbine drives rotation ofthe compressor via the shaft. The compressor draws ambient air 36 andprovides compressed air through an outlet to the intake manifold. Theturbocharged power system optionally includes a heat exchanger 38 alongthe intake manifold that reduces the temperature of the compressed airprior to delivery into the engine. Gases exhausted from the cylindersvia the combustion reaction are routed through the exhaust manifold todrive the turbine.

The turbocharged power system includes a turbocharger assist device 60mechanically connected to the turbocharger. In FIG. 1, the turbochargerassist device is connected to the turbocharger via a turbocharger driveshaft 58. The turbocharger assist device is an electric motor-generatorfor facilitating independent control of the turbocharger operation. Forexample, the turbocharger assist device may be a single shaft motor thatis driven by rotation of the turbine and/or compressor of theturbocharger via the turbocharger drive shaft. Alternatively, theturbocharger assist device may be a double shaft motor instead of asingle shaft. In the illustrated embodiment, the turbocharger assistdevice is shown at the end of the turbocharger drive shaft, such thatthe compressor is between the turbine and the turbocharger assistdevice. In an alternative embodiment, the turbocharger assist device maybe disposed between the compressor and the turbine or may be on theother side of the shaft such that the turbine is in the middle.

The turbocharger assist device is operable in two distinct operatingmodes to supply work to the turbocharger drive shaft (i.e. to applytorque to the shaft for rotation) in a first operating mode and removework from the turbocharger drive shaft (i.e. to be driven by the shaftto generate electric current) in a second operating mode. The firstoperating mode is referred to herein as a motor mode because theturbocharger assist device functions as a motor, and the secondoperating mode is referred to herein as a generator mode because theturbocharger assist device functions as a generator. The turbochargerassist device is electrically connected to the one or more loads via thepower control circuity. For example, in the generator mode, theturbocharger assist device may generate electric current based on therotation of the turbocharger to supply the electric current to the powercontrol circuitry for powering one or more of the loads, as described inmore detail herein.

A battery module 62 is present in the turbocharged power system shown inFIG. 1. The battery module includes one or more battery cells and/orother electrical storage devices. The battery module is electricallyconnected to the power control circuitry such that the battery module isconfigured to selectively receive current from the power controlcircuitry for charging the battery module and to supply current to thepower control circuitry for powering one or more devices, such as theloads or the turbocharger assist device. For example, in response to afirst operating condition, the power control circuit may direct electriccurrent from the battery module to one or more of the loads, and, inresponse to a second operating condition, the electric current from thebattery module may be directed to the turbocharger assist deviceoperating in the motor mode to drive the turbocharger.

The turbocharged power system includes a controller 40 for controllingthe operations of the power system. The controller may be an electroniclogic controller including one or more processors and associatedcircuitry. The controller may operate based on programmed instructionsstored in an electronic memory storage device 54 or hard-wired into thelogic of the controller. The controller is communicatively connected tomultiple sensors 42, 44, 46, 48, 50 that monitor various differentparameters of the engine and/or the turbocharger. For example, thesensors may include a pressure sensor 42, a temperature sensor 44, aspeed sensor 46, an ambient temperature sensor 48, and a mass flow ratesensor 50. However, various other sensors may be used to monitordifferent operating parameters of the engine and the turbocharger, suchas sensors that are used to monitor current, voltage, power, frequencyat the electrical terminals of the turbocharger assist device, angularposition of the turbocharger assist device, the battery, the variousloads, and/or the like. The controller is configured to receive sensorsignals 52 generated by the sensors. The sensor signals include dataindicative of the monitored operating parameters. The sensor signals maybe communicated to the controller via a wired or wireless communicationpathway.

The controller analyzes the received sensor signals and generatescontrol signals 51 in response based on the programmed instructions. Thecontrol signals are communicated to the power control circuitry forcontrolling the distribution of electric current among the loads, thealternator, the battery module, and the turbocharger assist device. Forexample, the control signals generated by the controller regulateapplication of work to, or extraction of work from, the turbocharger viathe turbocharger assist device. The power control circuitry therebycontrols the operation of the turbocharger. The control signals may becommunicated to the power control circuitry via a wired or wirelesscommunication pathway. For example, the turbocharged power systemoptionally may include a wireless communication device operably coupledto the controller. The wireless communication device includes atransceiver or a discrete transmitter and receiver, an antenna, andassociated circuitry for transmitting wireless control signals and/orreceiving wireless sensor signals.

The controller may implement operating control protocols or schemes forcontrolling the energy transfer between the turbocharger and the loadbased on operating parameters (e.g., conditions and/or settings) of theengine, the turbocharger, and/or the like. For example, the turbochargerassist device may be utilized to extract energy from the turbochargerand supply electric current to the load in a first range of operatingparameters, and the turbocharger assist device may be blocked fromsupplying current to the load in a different, second range of operatingparameters. In another example, the turbocharger assist device isselectively operable in both a generator mode and a motor mode. In thegenerator mode, the turbocharger assist device generates electriccurrent based on rotation of the turbocharger to power the load, asdescribed above. In the motor mode, the turbocharger assist devicefunctions as a motor to mechanically assist in rotating the rotors ofthe turbocharger to compress the air to the engine. For example, theturbocharger assist device receives electrical energy from a batterymodule, the alternator, and/or the load (e.g., a traction motor) andconverts the electrical energy into mechanical energy for spinning thecompressor rotor of the turbocharger. The various control protocolsdescribed herein may be adjusted or modified based onapplication-specific considerations and/or parameters. For example, theoperating parameters that are monitored, the threshold values and/orranges of the operating parameters utilized as triggering events, andthe actions taken in response to the monitored operating parameterscrossing the threshold values and/or ranges may be selectively variedwithin the scope of the inventive subject matter described herein. Theapplication-specific considerations and/or parameters that may affectthe control protocols include environmental conditions, the type of loadconnected to the turbocharger assist device, commanded operatingsettings of the engine, and/or the like.

In a non-limiting example control protocol, the turbocharger assistdevice may be operated in the motor mode during initial start-up of theengine in cold weather conditions. In the motor mode, the turbochargerassist device receives electrical energy supplied via the power controlcircuitry from one or more of the alternator, the battery module, or theloads. The turbocharger assist device uses the received electricalenergy to exert torque on the turbocharger via the turbocharger driveshaft (in addition to torque supplied from the turbine). The additionaltorque supports rotation of the compressor, permitting compression ofadditional air and/or at higher pressures for introduction into thecylinders of the engine. Conversely, during high-speed operation inwhich the engine is warmed up and operating at relatively high enginespeeds, the turbocharger assist device may be operated in the generatormode. In the generator mode, the turbocharger assist device extractswork from the turbocharger to generate electric current. Theturbocharger assist devices essentially forms an additional load on theturbocharger drive shaft, which decreases the rotational speed of theturbocharger drive shaft and therefore reduces the amount of air and/orthe pressure of the air available for introduction into the cylinders ofthe engine for combustion (relative to the turbocharger operatingwithout the extraction of work by the turbocharger assist device). Theelectric current generated by the turbocharger assist device is suppliedto the power control circuitry for powering one or more of the loads orcharging the battery module.

Another benefit of operating the turbocharger assist device in thegenerator mode is to avoid, or at least reduce the likelihood of, thecompressor of the turbocharger experiencing surge or excess speed due tofluctuations in the exhaust gas pressure, flow rate, temperature, andother parameters. By reducing the pressure of compressed air beingprovided to the engine, the turbocharger assist device reduces themaximum pressures achieved in the cylinders of the engine. Operating theturbocharger assist device in the generator mode reduces theturbocharger speed to maintain the speed below safe design limits whilerecovering useful energy in the process.

FIG. 2 is a schematic circuit diagram of a power delivery system 100according to an embodiment of the present disclosure. The power deliverysystem 100 includes an alternator 102, a turbocharger assist device 104,a battery module 106, a controller 108, inverters 110, loads 112,switches 114, and rectifiers 116. The power delivery system isconfigured to distribute electrical energy (e.g., current) among thealternator, the battery module, the turbocharger assist device, and theloads. The power delivery system 100 may represent a portion of theturbocharged power system 10 shown in FIG. 1. For example, thealternator 102 may represent the alternator 18; the turbocharger assistdevice 104 may represent the turbocharger assist device 60; the batterymodule 106 may represent the battery module 62; the controller 108 mayrepresent the controller 40; and the loads 112 may represent the loads22. The inverters 110, switches 114, and rectifiers 116 may representthe power control circuitry 20 shown in FIG. 1.

The inverters of the power delivery system are electronic devices orcircuitry that change direct current (DC) to alternating current (AC).Each of the inverters is electrically connected to a corresponding load.In FIG. 2, all of the inverters are electrically connected to differentrespective loads. Although FIG. 2 discloses inverters, other types ofconverter devices may be used instead of inverters or in addition toinverters based on application-specific requirements or goals. Forexample, other types of converter devices may include choppers, Hbridges, and the like.

A set 118 of inverters 110 are electrically connected to a primary bus120. The set 118 includes at least a first inverter 110A. In theillustrated embodiment, the set 118 has four inverters 110 that arecommonly connected to the primary bus. The primary bus 120 is anelectrically conductive pathway that is used to distribute electriccurrent to the inverters in the set. The primary bus includes orrepresents one or more bus bars, electrical cables, and/or the like. Theprimary bus may be rigid or flexible. The alternator is electricallyconnected to the primary bus via a first rectifier 116A. The rectifiers116 are electrical devices that convert AC current to DC current. Therectifiers may be three-phase diode rectifiers. The inverters in the setare configured to receive electric current from the alternator 102 viathe primary bus. For example, the alternator generates AC current basedon mechanical energy (e.g., torque) received from an engine (e.g., theengine 14 shown in FIG. 1). The AC current generated by the alternatoris converted to DC current by the first rectifier and is thereaftersupplied to the primary bus. The inverters in the set receive the DCcurrent from the primary bus and convert the DC current back to ACcurrent. The AC current is supplied by the inverters in the set to thecorresponding loads to power the loads. In the illustrated embodiment,the set of inverters are electrically connected to a set 124 of multipleloads 112. All of the loads in the set are powered by the electriccurrent generated by the alternator 102. In one or more embodiments,only the alternator powers the loads that are in the set connected tothe primary bus. For example, neither the battery module nor theturbocharger assist device supplies electric current to the primary bus.A DC bus system is shown for illustration, but the bus system could bean AC bus system.

The power delivery system 100 also includes a secondary bus 122 that isdiscrete from the primary bus. One of the inverters 110B, referred toherein as a second inverter, is electrically connected to the secondarybus. The second inverter is separate from the inverters in the set andis electrically isolated from the inverters in the set. For example, dueat least to the presence of circuit devices such as the rectifiers andthe switches, there is no electric current path from the primary bus tothe secondary bus or vice-versa. The secondary bus includes orrepresents one or more bus bars, electrical cables, and/or the like. Thesecond inverter is electrically connected to a corresponding load 112B,referred to herein as a second load. The second load is separate anddiscrete from the loads in the set 124. The second inverter supplieselectric current from the secondary bus to the second load.

The turbocharger assist device 104 is mechanically connected to aturbocharger (e.g., the turbocharger 12 shown in FIG. 1) which isoperably coupled to an engine. The turbocharger assist device iselectrically connected to the secondary bus. In the generator mode, theturbocharger assist device generates electric current based on rotationof the turbocharger. More specifically, the turbocharger assist deviceextracts energy from the exhaust gas-driven rotation of the turbine togenerate the electric current. The electric current can be directed tothe secondary bus where the second inverter supplies the electriccurrent to the second load to power the load. For example, theturbocharger assist device 104 generates AC current, which is convertedto DC current by a second rectifier 116B disposed along the secondarybus between the turbocharger assist device and the second inverter. TheDC current from the second rectifier is supplied to the second inverter,which converts the DC current back to AC current. The second load ispowered by the AC current from the second inverter. The rectifier 116Bis shown for illustration. Optionally, instead of the rectifier, abi-directional converter can be installed and used to power the AC sidefrom the DC side.

The battery module 106 is electrically connected to both the secondarybus and the turbocharger assist device. For example, the battery moduleis selectively controlled to supply electric current to the secondarybus for powering the second load. When the turbocharger assist device isin the motor mode, the battery module can supply electric current to theturbocharger assist device for powering the turbocharger (e.g., exertingtorque to rotate the compressor). Optionally, the turbocharger assistdevice in the motor mode may receive electric current from the secondload instead of, or in addition to, receiving current from the batterymodule. The battery module may also be selectively charged by theturbocharger assist device when in the generator mode. In this describedembodiment in which the turbocharger assist device can be charged by thesecond load and/or the battery module, the converter 116B may beconfigured for bidirectional current flow, like an inverter.

The power delivery system includes switches 114 that are operated by thecontroller 108 to control the distribution of electric current throughthe power delivery system. The controller is operably coupled to theswitches via a wired or wireless communication pathway. The controllerincludes one or more processors 126 (e.g., microprocessors, integratedcircuits, field programmable gate arrays, or the like). For example, thecontroller generates control signals for actuating the switches. Theswitches include a first switch 114A associated with the turbochargerassist device. The switches also include a second switch 114B associatedwith the battery module and a third switch 114C associated with thealternator. The switches are actuatable to establish the conduction ofcurrent when in a closed, conducting state, and to block currentconduction when in an open, non-conducting state. Each of the switchesmay represent or include a contactor, an insulated gate bipolartransistor (IGBT), a metal oxide semiconductor field effect transistor(MOSFET), a silicon carbide (SiC) MOSFET, a gallium nitride (GaN)device, a bipolar junction transistor (BJT), a metal oxide semiconductorcontrolled thyristor (MCTs), a silicon controlled rectifier (SCR), apower diode, a tap, a gat turn-off thyristor, a diode AC switch (DIAC),a triode AC switch (TRIAC), or the like.

The turbocharger assist device is electrically connected to thesecondary bus via the first switch. The first switch is selectivelyclosed to permit (e.g. allow or enable) the turbocharger assist deviceto supply electric current to the secondary bus in the generator modeand receive electric current from the secondary bus in the motor mode.The first switch is selectively opened to disconnect the turbochargerassist device from the secondary bus. The battery module is electricallyconnected to the secondary bus via the second switch. The alternator iselectrically connected to the secondary bus via the third switch. Insome embodiments the third switch associated with the alternator may bereferred to as a second switch, such as if the power delivery systemlacks the battery module. Like the first switch, the second and thirdswitches are selectively closed to permit current flow between thesecondary bus and the associated devices (e.g., the battery module andalternator, respectively), and are selectively opened to disconnect theassociated devices from the secondary bus. The first, second, and thirdswitches are independently controlled by the controller. The controllermay operate the switches based on programmed control protocols (e.g.,settings, schemes, etc.) saved within a memory storage device (e.g., thememory device 54 shown in FIG. 1). The control settings may be stored ina database. The controller may select which control setting to implementat a given time based on operating parameters of the engine and/orturbocharger. For example, the memory storage device may include alook-up table that associates operating parameters or conditions withdifferent control settings for controlling the switches.

In one or more embodiments, the secondary bus has a lower voltage thanthe primary bus. For example, the alternator may supply a greater amountof electrical energy or power to the primary bus than the amount ofelectrical energy or power supplied by the turbocharger assist device(or the battery module) to the secondary bus. The voltage of the primarybus may be two times or more the voltage on the secondary bus. Due tothe variation in power levels, the primary bus is able to power greaterloads or a greater number of equivalent loads than the secondary bus.Although the voltage on the secondary bus is low, the secondary bus isefficient because the electric current on the secondary bus may beentirely attributable to the energy salvaged from engine exhaust gasesand extracted from the turbocharger. In an embodiment, the inverters inthe set may be supplied electric current via the primary busconcurrently with the second inverter being supplied current via thesecondary bus. Thus, the first load and the other loads in the set maybe concurrently powered with the second load.

The schematic diagram of FIG. 2 illustrates the main components of thepower delivery system according to an embodiment. The power deliverysystem optionally may include additional circuit devices and elementsthat are not shown in FIG. 2. The power delivery system may includedifferent types of components, different arrangements of components,and/or different numbers of components in alternative embodiments. Forexample, in one alternative embodiment, the power delivery system maylack the battery module. In another alternative embodiment, there may begreater or less than four inverters connected to the primary bus and/orgreater than one inverter connected to the secondary bus. Furthermore,at least some of the inverters may be configured to supply electriccurrent to the same loads instead of each inverter being electricallyconnected to a different, respective load. In yet another alternativeembodiment, the number, type, and/or arrangement of switches andrectifiers may be modified. For example, instead of the first and thirdswitches 114A, 114C, the power delivery system may include a third dioderectifier connected to the second rectifier 116B, which could becontrolled to provide the same functionality as the two switches 114A,114C.

As described in greater detail below, the power delivery system mayfacilitate retrofit applications. For example, the inverter 110B andload 112B may have been connected to the primary bus 120 previously toreceive power from the primary bus 120. A retrofit operation may beperformed to achieve the illustrated arrangement with littlemodification. After the retrofit, the fuel efficiency and/or emissionsmay be improved relative to the conditions before the retrofit.

FIG. 3 illustrates a vehicle 300 representing an example application ofthe power delivery system 100 shown in FIG. 2. The vehicle 300 is aground-based vehicle that includes multiple wheelsets 302. FIG. 3 is abottom view of the vehicle showing four wheelsets 302. Each wheelsetincludes at least two wheels 304 and an axle 306. The wheels are coupledto the axle and spaced apart along the length of the axle. The vehicleincludes multiple traction motors 308 mechanically connected to thewheelsets. For example, each traction motor is mechanically connectedvia a gear set to a corresponding wheelset. The traction motors are usedto propel the vehicle along the ground. The traction motors receiveelectric current and generate torque to rotate the wheelsets forpropelling the vehicle. The vehicle in FIG. 3 has four traction motors,and each traction motor is mechanically connected to a different one ofthe four wheelsets. The vehicle also has an auxiliary motor 310 that isused for powering one or more auxiliary loads onboard the vehicle, suchas lights, fans, furnaces, air-conditioners, electronics, and/or thelike. The auxiliary motor is not mechanically connected to any of thewheelsets. In a non-limiting example, the vehicle is a rail-basedvehicle, such as a locomotive.

The power delivery system 100 shown in FIG. 2 is disposed onboard thevehicle as a portion of a vehicle propulsion system 301 for propellingthe vehicle along a route. Although all of the components of the powerdelivery system may be installed onboard the vehicle, only a subset ofthe components are illustrated in FIG. 3 for clarity. The first inverter110A of the power delivery system is electrically connected to a firsttraction motor 308A of the traction motors, which represents the firstload 112A shown in FIG. 2. The second inverter 110B is electricallyconnected to a second traction motor 308B of the traction motors, whichrepresents the second load 112B shown in FIG. 2. Electric current on theprimary bus 120 is supplied by the first inverter to the first tractionmotor which generates mechanical energy (e.g., torque) to rotate a firstwheelset 302A of the vehicle. Electric current on the secondary bus 122is supplied by the second inverter to the second traction motor whichgenerated mechanical energy to rotate a second wheelset 302B. In one ormore embodiments, when the turbocharger assist device 104 (shown in FIG.2) is operated in the generator mode, the turbocharger assist device 104supplies electric current to the secondary bus, which powers the secondtraction motor to rotate the wheels of the second wheelset. Because theelectric current generated by the turbocharger assist device 104 isbased on the mechanical exhaust gas-driven rotation of the turbine ofthe turbocharger, energy from the engine exhaust gases is utilized forrotating the second wheelset to propel the vehicle in combination withthe current supplied to the primary bus by the alternator.

The third and fourth traction motors 308C, 308D of the vehicle areelectrically connected to two other inverters 110 in the set 118connected to the primary bus. The auxiliary motor 310 is connected toanother inverter in the set. As shown in FIG. 3, electrical energy onthe primary bus is used to power three of the four traction motors (allbut the second traction motor 308B) and the auxiliary motor. Therefore,the alternator supplies electrical energy for powering three tractionmotors 308A, 308C, 308D, and the turbocharger assist device, based onthe rotation of the turbine of the turbocharger, supplies electricalenergy for powering the second traction motor 308B. In an embodiment,all four traction motors 308A-308D may be concurrently powered toprovide tractive effort for propelling the vehicle. The three tractionmotors 308A, 308C, 308D connected to the primary bus may each provide agreater amount of tractive effort than the second traction motor 308Bconnected to the secondary bus because the alternator may supply agreater amount (e.g., voltage) of electrical energy than theturbocharger assist device. In a non-limiting example, the threetraction motors 308A, 308C, 308D may each provide 1000 horsepower (HP)at a given tractive setting (e.g., notch setting), and the secondtraction motor 308B provides 200 HP. Thus, at the given tractivesetting, the vehicle is propelled by a combined 3200 HP (1000*3+200).

In an embodiment, the vehicle may be retrofit to accommodate the powerdelivery system described herein. For example, prior to retrofitting,all four of the traction motors 308A-D may be commonly connected to theprimary bus. Each of the traction motors may be operated to provide 800HP in order for the vehicle to be propelled by the 3200 HP described inthe hypothetical example above. All of the electrical energy forpowering the propulsion of the vehicle stems from the electric currentgenerated by the alternator and supplied to the primary bus. Theretrofit operation includes electrically isolating one of the tractionmotors (e.g., the second traction motor 308B) from the primary bus andconnecting that traction motor to a secondary bus connected to theturbocharger assist device. The traction motor may be electricallyisolated by disconnecting the traction motor from the primary bus. Themechanical connection between that separated traction motor and theassociated wheelset may be left intact. The retrofit operation alsoincludes installing the other devices, circuit elements, directionalelements, and switching elements of the power delivery system shown inFIG. 2, such as the switches 114A-C, the rectifiers 116A-B, theturbocharger assist device 104 (if not already present on the vehicle),the optional battery module 106, and the like. The retrofit operationmay be relatively simple and cost-effective for a mechanic. Optionally,instead of a traction motor, the load 112B could represent an auxiliarydevice, such as a fan, an air conditioner, a compressor, a power supply,or the like.

Retrofitting vehicles to operably connect a turbocharger assist deviceto one of the traction motors of the vehicle can significantly increasethe efficiency of the vehicle because a portion of the tractive effortpropelling the vehicle is generated by salvaging energy from the engineexhaust gases which drive the turbocharger. The alternator coupled tothe engine is not relied on for providing all of the tractive effort.When the second traction motor is powered by the electric currentgenerated by the turbocharger assist device to contribute 200 HP, thealternator is only relied on for generating 3000 HP to achieve a net3200 HP power output. Thus, 6% of the total power output(200/3200=6.25%) is essentially free because it is attributable toenergy recycled from the engine exhaust gases.

Furthermore, when the turbocharger assist device is in the motor mode toprovide torque for rotating the compressor of the turbocharger, theelectric current for powering the turbocharger assist device may besupplied by the second traction motor 308B. For example, the secondtraction motor may be selectively operated as a generator duringregenerative braking. When tractive effort from the second tractionmotor is not needed, such as when the vehicle is driving along adecline, braking, or the other tractive motors can provide all of thedesired tractive effort, the second traction motor can be operated as agenerator to generate electric current the rotation of the associatedwheelset 302B caused by friction with the ground surface. The electriccurrent generated by the second traction motor can be supplied via thesecondary bus to the turbocharger assist device, which functions as amotor to generate mechanical energy (e.g., torque) for rotating theturbocharger. For example, as shown in FIG. 1, the turbocharger assistdevice may exert torque on the turbocharger drive shaft 58 whichincreases the rotational speed of the compressor 24. Increasing thecompressor speed increases the amount and/or pressure of the air fed tothe cylinders of the engine, which can increase the power output of theengine. Thus, the rotation of the wheels and axle of one of thewheelsets can be used to power the turbocharger.

To regulate the temperature of the turbocharger assist device, theturbocharger assist device can be installed on the vehicle in a locationthat receives cooling airflow. The presence of the diode rectifiers 116enable spacing the turbocharger assist device a significant distance(e.g., one to five meters) away from the inverter 110B and tractionmotor 308B. In a non-limiting example, the turbocharger assist devicecan be installed within or adjacent to an air plenum that conveyscooling air. The cooling air through the plenum dissipates heat from theturbocharger assist device during operation.

In alternative embodiments, the vehicle may have other than fourtraction motors, more than one auxiliary motor, and/or other than fourwheelsets. For example, the vehicle may be a locomotive that has sixwheelsets and six traction motors. The locomotive may be retrofit bydisconnecting one of the six traction motors from the primary bus suchthat the turbocharger assist device powers one traction motor and thealternator powers the other five. Although the vehicle is described as alocomotive, the power delivery system described herein may be installedwithin the propulsion systems of various other types of vehiclescontaining turbocharged engines, such as automobiles, trucks, miningequipment, aircrafts, marine vessels, and the like. Furthermore, FIG. 3represents a vehicular application of the power delivery system, but thepower delivery system can be used in various non-vehicle applications.Some non-limiting examples of non-vehicle applications includestationary engine drive systems (e.g., generator sets) and otherindustrial electric machinery.

FIG. 4 is a graph 400 depicting a control protocol for controlling asupply of electric current to a load according to an embodiment. Thegraph plots an operating parameter along the vertical axis 402 and timealong the horizontal axis 404. A trendline 405 displays the value of theoperating parameter over time. The control protocol may be implementedby the one or more processors 126 of the controller 108 of the powerdelivery system 100 shown in FIG. 2. The one or more processors mayperform the control protocol based on programmed instructions stored ina memory device or hard-wired into the logic of the controller. Theoperating parameter represents an operating parameter of a turbochargedengine, such as a parameter associated with operation of the engine orthe turbocharger. Some non-limiting examples of the operating parameterinclude a compressor pressure ratio of the turbocharger, rotationalspeed of the turbocharger, intake manifold temperature, intake manifoldpressure, mass flow rate of air entering the engine, exhaust manifoldtemperature, exhaust manifold pressure, mass flow rate of exhaust gasexiting the engine, or the like. The one or more processors areconfigured to monitor the operating parameter over time based onreceived sensor signals. The sensor signals are generated by sensorsinstalled on or proximate to the engine and the turbocharger, such asthe sensors 42, 44, 46, 48, 50 shown in FIG. 1.

In an embodiment, the protocol defines a first designated threshold 406and a second designated threshold 408 for the operating parameter. Thefirst designated threshold is greater than the second designatedthreshold. The values of the first and second designated thresholds maybe selected based on application-specific and parameter-specificconsiderations. As shown by the trendline 405, the monitored operatingparameter exceeds the first designated threshold at time t₁. Inresponse, the one or more processors are configured to allow theturbocharger assist device 104 to supply electric current to the secondinverter 110B via the secondary bus 122 to power the second load 112B.For example, the one or more processors may generate a control signalthat is transmitted to the first switch 114A to close the first switch,establishing a conductive path between the turbocharger assist deviceand the second load. Optionally, the second and third switches 114B,114C at time ti are controlled to be open and non-conducting such thatthe second inverter only receives the electric current supplied by theturbocharger assist device. The turbocharger assist device suppliescurrent to the secondary bus during a first time period 410 until theoperating parameter falls below the first designated threshold at timet₂. At time t₂, the one or more processors may open the first switch tobreak the conductive pathway and block the turbocharger assist devicefrom supplying current to the secondary bus.

Optionally, no current is supplied to the secondary bus for powering thesecond load during a second time period 411 from time t₂ until theoperating parameter falls below the second designated threshold at timet₃. The second load may not be powered during the second time period. Attime t₃, the one or more processors may be configured to close thesecond switch 114B, close the third switch 114C, or close both thesecond and third switches. In one example, the processors close thesecond switch 114B only to allow the battery module 106 to supplyelectric current to the secondary bus for powering the second load 112B.The battery module 106 supplies current to the secondary bus during athird time period 412 from time t₃ until the operating parameter exceedsthe second designated threshold at time t₄. If the battery module is notcharged or not present, then at time t₃ the processors may close thethird switch 114C to allow the alternator 102 to supply electric currentto the secondary bus for powering the second load during the third timeperiod.

The example control protocol graphed in FIG. 4 indicates that the sourceof electric current on the secondary bus 122 for powering the secondload 112B may change over time based on the monitored operatingparameter. For example, the second load is powered by the turbochargerassist device 104 during the first time period 410, is not powered atall during the second time period 411, and is powered by the batterymodule 106 and/or the alternator 102 during the third time period 412.The turbocharger assist device powers the second load when the operatingparameter is greater than the first designated threshold because at thishigh parameter range, the engine does not require much work from theturbocharger to compress the incoming air, so some of the energy can beextracted to power the second load. The turbocharger assist device isnot used to power the second load when the operating parameter is lessthan the first designated threshold so that energy is not extracted fromthe turbocharger to power the load. For example, the engine may operatemore efficiently at lower parameter levels when all of the energysalvaged from the engine exhaust gases is utilized by the turbochargerfor compressing the incoming air.

Optionally, the protocol may define a third designated threshold that isless than the second designated threshold. When the operating parameteris less than the third designated threshold, the one or more processorsare configured to operate the turbocharger assist device in the motormode to exert torque on the turbocharger drive shaft to increase therotational speed (or maintain the rotational speed) of the compressor.Optionally, the second load is the traction motor 308B, and the one ormore processors are configured to open the switches 114B, 114C to blockthe conductive path between the second load and the battery module 106and alternator 102, respectively, and to close the first switch 114A.The traction motor 308B generates electric current based on the rotationof the associated wheelset 302B and supplies the electric current to theturbocharger assist device via the secondary bus to power theturbocharger assist device in the motor mode. Therefore, at the lowestparameter range, such as when the vehicle 300 is moving at the lowestnotch settings, the rotating wheelset connected to the second tractionmotor can be used to generate power for powering the turbocharger tosupport the compression of air into the engine.

FIG. 5 is a flow chart 500 of a method for delivering power from aturbocharged engine according to an embodiment. The method may beperformed entirely or in part by the one or more processors 125 of thecontroller 108 shown in FIG. 2. Optionally, the method may includeadditional steps, fewer steps, and/or different steps than theillustrated flow chart. The method in the illustrated embodiment isperformed on a vehicle propulsion system on a vehicle, but the methodcan also be performed on other types of turbocharged vehicles as well asnon-vehicle applications, such as stationary industrial machinery.

The method begins at 502, at which electric current is supplied from analternator to a first inverter via a primary bus of a power deliverysystem. The alternator generates the electric current based onmechanical energy received from an engine. At 504, the first invertersupplies the electric current to a first traction motor, whichrepresents a first load. The first traction motor is controlled togenerate tractive effort based on the received electric current. Thetractive effort propels movement of the vehicle.

At 505, an operating parameter is monitored relating to one or more ofthe engine or the turbocharger. The turbocharger is operably coupled tothe engine. The operating parameter may be monitored using sensors thatare installed on or proximate to the engine and/or turbocharger. Forexample, the sensors may generate sensor signals including datarepresentative of various operating parameters, and the sensor signalsare communicated to the one or more processors. At 506, a determinationis made whether an operating parameter is greater than a designatedthreshold. The designated threshold may be stored in an accessibledatabase or hardwired into the logic of the one or more processors. Theone or more processors may automatically make the determination based onthe sensor signals received from one or more sensors.

If the operating parameter is greater than the designated threshold, themethod continues to 508 and electric current is supplied from aturbocharger assist device to a second inverter via a secondary bus ofthe power delivery system. The turbocharger assist device operates in agenerator mode to supply current to the secondary bus. The supply ofcurrent may be enabled by closing a switch to establish a conductivepathway from the turbocharger assist device to the second inverter viathe secondary bus. At 510, the second inverter supplies the electriccurrent to a second traction motor of the vehicle, which represents asecond load. Alternatively, the second load may be an auxiliary loadinstead of a traction motor. The secondary bus is discrete from theprimary bus. The turbocharger assist device is mechanically connected tothe turbocharger. The turbocharger assist device is configured togenerate electric current based on rotation of a rotor of theturbocharger. For example, the rotor rotation (e.g., the turbine and/orcompressor) rotates a turbocharger drive shaft that is mechanicallyconnected to the turbocharger assist device. The turbocharger assistdevice converts the mechanical rotation into electrical energy suppliedas current to the secondary bus for powering the second traction motor.The second traction motor is controlled to generate tractive effortbased on the received electric current to propel movement of thevehicle. Optionally, the first traction motor may be supplied electriccurrent from the alternator via the primary bus concurrently with thesecond traction motor being supplied electric current from theturbocharger assist device via the secondary bus.

If, on the other hand, the operating parameter is determined to not begreater than the designated threshold, the method continues to 512. At512, the turbocharger assist device is blocked from supplying current tothe second inverter. Therefore, the second traction motor is not poweredby the turbocharger assist device when the operating parameter is lowerthan the designated threshold. Optionally, the second traction motor maybe powered by a battery module and/or the alternator at operatingparameter ranges below the designated threshold.

At 514, a determination is made whether to switch from the generatormode of the turbocharger assist device to a motor mode. Thedetermination may be based on the operating parameter that is monitoredand/or other parameters, such as a speed of the vehicle, a grade of theroute, a braking status of the vehicle, or the like. For example,designated threshold described in 506 may be a first designatedthreshold, and the mode may switch if the operating parameter is below asecond designated threshold that is lower than the first designatedthreshold. If it is determined to switch to motor mode, the methodcontinues to 516. At 516, the second traction motor generates electriccurrent which is supplied from the second inverter via the secondary busto the turbocharger assist device. The turbocharger assist deviceconverts the electric current into mechanical energy for rotating therotor of the turbocharger. In the motor mode, the turbocharger assistdevice supports the compression of air that is supplied to the engine byexerting a torque on the compressor rotor.

In one or more embodiments, a power delivery system includes a firstinverter, a second inverter, and a turbocharger assist device. The firstinverter is electrically connected to a primary bus and configured toreceive electric current from an alternator via the primary bus tosupply the electric current to a first load. The alternator generatesthe electric current based on mechanical energy received from an engine.The second inverter is electrically connected to a secondary bus that isdiscrete from the primary bus. The turbocharger assist device ismechanically connected to a turbocharger operably coupled to the engine.The turbocharger assist device is electrically connected to thesecondary bus and configured to generate electric current based onrotation of a rotor of the turbocharger. The second inverter isconfigured to receive the electric current generated by the turbochargerassist device via the secondary bus to supply the electric current to asecond load.

Optionally, the first inverter is one of a set of multiple inverterselectrically connected to the primary bus, and the inverters in the setare electrically isolated from the second inverter.

Optionally, the first and second inverters are disposed onboard avehicle and the first and second loads are first and second tractionmotors, respectively, for propelling the vehicle.

Optionally, the vehicle has multiple wheelsets. Each wheelset includesat least two wheels. The first traction motor is mechanically connectedto a first wheelset of the multiple wheelsets and the second tractionmotor is mechanically connected to a second wheelset of the multiplewheelsets such that rotation of the rotor of the turbocharger isutilized for rotating the second wheelset to propel the vehicle.

Optionally, the turbocharger assist device is configured to generateelectric current based on the rotation of the rotor of the turbochargerfor powering the second traction motor in a generator mode. In a motormode, the turbocharger assist device is configured to receive electriccurrent from the second traction motor via the secondary bus and convertthe electric current into mechanical energy for rotating the rotor ofthe turbocharger.

Optionally, the first inverter is configured to receive electric currentfrom the alternator via the primary bus concurrently with the secondinverter receiving electric current from the turbocharger assist devicevia the secondary bus.

Optionally, the turbocharger assist device is electrically connected tothe secondary bus via a switch. The power delivery system furtherincludes one or more processors operably connected to the switch andconfigured to monitor an operating parameter of the engine and/or theturbocharger. The one or more processors are configured to close thefirst switch to allow the turbocharger assist device to supply electriccurrent to the second inverter via the secondary bus responsive to theoperating parameter being greater than a designated threshold.

Optionally, the turbocharger assist device is electrically connected tothe secondary bus via a switch. The power delivery system furtherincludes one or more processors operably connected to the switch andconfigured to monitor an operating parameter of the engine and/or theturbocharger. The one or more processors are configured to open thefirst switch to block the turbocharger assist device from supplyingelectric current to the second inverter via the secondary bus responsiveto the operating parameter being below a designated threshold.

Optionally, the turbocharger assist device is electrically connected tothe secondary bus via a first switch. The power delivery system furtherincludes a battery module electrically connected to the secondary busvia a second switch. The first switch is selectively closed to allow theturbocharger assist device to supply electric current to the secondinverter, and the second switch is selectively closed to allow thebattery module to supply electric current to the second inverter.

Optionally, the power delivery system further includes one or moreprocessors operably coupled to the first and second switches andconfigured to monitor an operating parameter of the engine and/or theturbocharger. The one or more processors are configured to close thefirst switch to allow the turbocharger assist device to supply electriccurrent to the second inverter responsive to the operating parameterbeing greater than a first designated threshold. The one or moreprocessors are configured to close the second switch to allow thebattery module to supply electric current to the second inverterresponsive to the operating parameter being less than a seconddesignated threshold that is less than the first designated threshold.

Optionally, the power delivery system further includes a three-phasediode rectifier disposed along the secondary bus between theturbocharger assist device and the second inverter.

Optionally, the turbocharger assist device is electrically connected tothe secondary bus via a first switch and the alternator is electricallyconnected to the secondary bus via a second switch. The first switch isselectively closed to allow the turbocharger assist device to supplyelectric current to the second inverter. The second switch isselectively closed to allow the alternator to supply electric current tothe second inverter.

Optionally, the power delivery system further includes one or moreprocessors operably coupled to the first and second switches andconfigured to monitor an operating parameter of the engine and/or theturbocharger. The one or more processors are configured to close thefirst switch to allow the turbocharger assist device to supply electriccurrent to the second inverter responsive to the operating parameterbeing greater than a first designated threshold. The one or moreprocessors are configured to close the second switch to allow thealternator to supply electric current to the second inverter responsiveto the operating parameter being less than a second designated thresholdthat is less than the first designated threshold.

In one or more embodiments, a method (e.g., for delivering power)includes supplying electric current from an alternator to a firstinverter via a primary bus of a power delivery system for the firstinverter to supply the electric current to a first load. The alternatorgenerates the electric current based on mechanical energy received froman engine. The method also includes supplying electric current from aturbocharger assist device to a second inverter via a secondary bus ofthe power delivery system for the second inverter to supply the electriccurrent to a second load. The secondary bus is discrete from the primarybus. The turbocharger assist device is mechanically connected to aturbocharger that is operably coupled to the engine. The turbochargerassist device is configured to generate electric current based onrotation of a rotor of the turbocharger.

Optionally, the electric current from the alternator to the firstinverter via the primary bus is concurrently supplied with the electriccurrent from the turbocharger assist device to the second inverter viathe secondary bus.

Optionally, the first and second inverters are disposed onboard avehicle and the first and second loads are first and second tractionmotors, respectively. The method also includes controlling the first andsecond traction motors to generate tractive effort to propel movement ofthe vehicle. The tractive effort is generated based on the electriccurrent supplied from the alternator through the first inverter to thefirst traction motor and the electric current supplied from theturbocharger assist device through the second inverter to the secondtraction motor.

Optionally, the electric current is supplied from the turbochargerassist device to the second inverter for powering the second tractionmotor in a generator mode. The method further includes supplying,responsive to switching to a motor mode, electric current generated bythe second traction motor from the second inverter to the turbochargerassist device via the secondary bus for the turbocharger assist deviceto convert the electric current into mechanical energy for rotating therotor of the turbocharger.

Optionally, the method further includes monitoring, via one or moreprocessors, an operating parameter of the engine and/or theturbocharger. The electric current is supplied from the turbochargerassist device to the second inverter for powering the second loadresponsive to the operating parameter being greater than a designatedthreshold.

Optionally, the method further includes monitoring, via one or moreprocessors, an operating parameter of the engine and/or theturbocharger. The method also includes blocking the turbocharger assistdevice from supplying electric current to the second inverter via thesecondary bus responsive to the operating parameter being below adesignated threshold.

In one or more embodiments, a vehicle propulsion system includes analternator, a turbocharger, a turbocharger assist device, first andsecond traction motors, a first inverter, and a second inverter. Thealternator is configured to be disposed onboard a vehicle and togenerate electric current based on mechanical energy received from anengine. The turbocharger is operably coupled to the engine. Theturbocharger assist device is mechanically connected to the turbochargerand configured to generate electric current based on rotation of a rotorof the turbocharger. The first and second traction motors aremechanically connected to first and second wheelsets, respectively. Eachof the first and second wheelsets includes at least two wheels. Thefirst traction motor is electrically isolated from the second tractionmotor. The first inverter is electrically connected to the firsttraction motor and to the alternator via a primary bus. The firstinverter is configured to receive the electric current generated by thealternator to power the first traction motor to rotate the wheels of thefirst wheelset for propelling movement of the vehicle. The secondinverter is electrically connected to the second traction motor and tothe turbocharger assist device via a secondary bus. The second inverteris configured to receive the electric current generated by theturbocharger assist device to power the second traction motor to rotatethe wheels of the second wheelset for propelling the movement of thevehicle.

The above description is illustrative and not restrictive. For example,the above-described embodiments (and/or aspects thereof) may be used incombination with each other. In addition, many modifications may be madeto adapt a particular situation or material to the teachings of theinventive subject matter without departing from its scope. While thedimensions and types of materials described herein define the parametersof the inventive subject matter, they are by no means limiting and areexample embodiments. Many other embodiments will be apparent to one ofordinary skill in the art upon reviewing the above description. Thescope of the inventive subject matter should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

This written description uses examples to disclose several embodimentsof the inventive subject matter and to enable one of ordinary skill inthe art to practice the embodiments of inventive subject matter,including making and using any devices or systems and performing anyincorporated methods. The patentable scope of the inventive subjectmatter is defined by the claims, and may include other examples thatoccur to one of ordinary skill in the art. Such other examples arewithin the scope of the claims if they have structural elements that donot differ from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

The foregoing description of certain embodiments of the inventivesubject matter will be understood when read in conjunction with theappended drawings. To the extent that the figures illustrate diagrams ofthe functional blocks of various embodiments, the functional blocks arenot necessarily indicative of the division between hardware circuitry.Thus, for example, one or more of the functional blocks (for example,processors or memories) may be implemented in a single piece of hardware(for example, a general-purpose signal processor, microcontroller,random access memory, hard disk, and the like). Similarly, the programsmay be stand-alone programs, may be incorporated as subroutines in anoperating system, may be functions in an installed software package, andthe like. The various embodiments are not limited to the arrangementsand instrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the inventive subjectmatter are not intended to be interpreted as excluding the existence ofadditional embodiments that incorporate the recited features. Moreover,unless explicitly stated to the contrary, embodiments “comprising,”“including,” or “having” an element or a plurality of elements having aparticular property may include additional such elements not having thatproperty. In the appended claims, the terms “including” and “in which”are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Moreover, in the following claims, the terms“first,” “second,” and “third,” etc. are used merely as labels, and arenot intended to impose numerical requirements on their objects. Further,the limitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. § 112 (f), unless and until such claim limitationsexpressly use the phrase “means for” followed by a statement of functionvoid of further structure.

What is claimed is:
 1. A power delivery system comprising: a firstinverter electrically connected to a primary bus and configured toreceive electric current from an alternator via the primary bus tosupply the electric current to a first load, the alternator generatingthe electric current based on mechanical energy received from an engine;a second inverter electrically connected to a secondary bus that isdiscrete from the primary bus; and a turbocharger assist devicemechanically connected to a turbocharger operably coupled to the engine,the turbocharger assist device electrically connected to the secondarybus and configured to generate electric current based on rotation of arotor of the turbocharger, wherein the second inverter is configured toreceive the electric current generated by the turbocharger assist devicevia the secondary bus to supply the electric current to a second load.2. The power delivery system of claim 1, wherein the first inverter isone of a set of multiple inverters electrically connected to the primarybus, and the inverters in the set are electrically isolated from thesecond inverter.
 3. The power delivery system of claim 1, wherein thefirst and second inverters are disposed onboard a vehicle and the firstand second loads are first and second traction motors, respectively, forpropelling the vehicle.
 4. The power delivery system of claim 3, whereinthe vehicle has multiple wheelsets, each wheelset including at least twowheels, wherein the first traction motor is mechanically connected to afirst wheelset of the multiple wheelsets and the second traction motoris mechanically connected to a second wheelset of the multiple wheelsetssuch that rotation of the rotor of the turbocharger is utilized forrotating the second wheelset to propel the vehicle.
 5. The powerdelivery system of claim 3, wherein the turbocharger assist device isconfigured to generate electric current based on the rotation of therotor of the turbocharger for powering the second traction motor in agenerator mode, and, in a motor mode, the turbocharger assist device isconfigured to receive electric current from the second traction motorvia the secondary bus and convert the electric current into mechanicalenergy for rotating the rotor of the turbocharger.
 6. The power deliverysystem of claim 1, wherein the first inverter is configured to receiveelectric current from the alternator via the primary bus concurrentlywith the second inverter receiving electric current from theturbocharger assist device via the secondary bus.
 7. The power deliverysystem of claim 1, wherein the turbocharger assist device iselectrically connected to the secondary bus via a switch, and the powerdelivery system further comprises one or more processors operablyconnected to the switch and configured to monitor an operating parameterof one or more of the engine or the turbocharger, wherein the one ormore processors are configured to close the first switch to allow theturbocharger assist device to supply electric current to the secondinverter via the secondary bus responsive to the operating parameterbeing greater than a designated threshold.
 8. The power delivery systemof claim 1, wherein the turbocharger assist device is electricallyconnected to the secondary bus via a switch, and the power deliverysystem further comprises one or more processors operably connected tothe switch and configured to monitor an operating parameter of one ormore of the engine or the turbocharger, wherein the one or moreprocessors are configured to open the first switch to block theturbocharger assist device from supplying electric current to the secondinverter via the secondary bus responsive to the operating parameterbeing below a designated threshold.
 9. The power delivery system ofclaim 1, wherein the turbocharger assist device is electricallyconnected to the secondary bus via a first switch, and the powerdelivery system further comprises: a battery module electricallyconnected to the secondary bus via a second switch, wherein the firstswitch is selectively closed to allow the turbocharger assist device tosupply electric current to the second inverter and the second switch isselectively closed to allow the battery module to supply electriccurrent to the second inverter.
 10. The power delivery system of claim9, further comprising one or more processors operably coupled to thefirst and second switches and configured to monitor an operatingparameter of one or more of the engine or the turbocharger, wherein theone or more processors are configured to close the first switch to allowthe turbocharger assist device to supply electric current to the secondinverter responsive to the operating parameter being greater than afirst designated threshold, and wherein the one or more processors areconfigured to close the second switch to allow the battery module tosupply electric current to the second inverter responsive to theoperating parameter being less than a second designated threshold thatis less than the first designated threshold.
 11. The power deliverysystem of claim 1, further comprising a three-phase diode rectifierdisposed along the secondary bus between the turbocharger assist deviceand the second inverter.
 12. The power delivery system of claim 1,wherein the turbocharger assist device is electrically connected to thesecondary bus via a first switch and the alternator is electricallyconnected to the secondary bus via a second switch, wherein the firstswitch is selectively closed to allow the turbocharger assist device tosupply electric current to the second inverter, and the second switch isselectively closed to allow the alternator to supply electric current tothe second inverter.
 13. The power delivery system of claim 12, furthercomprising one or more processors operably coupled to the first andsecond switches and configured to monitor an operating parameter of oneor more of the engine or the turbocharger, wherein the one or moreprocessors are configured to close the first switch to allow theturbocharger assist device to supply electric current to the secondinverter responsive to the operating parameter being greater than afirst designated threshold, and wherein the one or more processors areconfigured to close the second switch to allow the alternator to supplyelectric current to the second inverter responsive to the operatingparameter being less than a second designated threshold that is lessthan the first designated threshold.
 14. A method comprising: supplyingelectric current from an alternator to a first inverter via a primarybus of a power delivery system for the first inverter to supply theelectric current to a first load, the alternator generating the electriccurrent based on mechanical energy received from an engine; andsupplying electric current from a turbocharger assist device to a secondinverter via a secondary bus of the power delivery system for the secondinverter to supply the electric current to a second load, the secondarybus being discrete from the primary bus, the turbocharger assist devicemechanically connected to a turbocharger that is operably coupled to theengine, the turbocharger assist device configured to generate electriccurrent based on rotation of a rotor of the turbocharger.
 15. The methodof claim 14, wherein the electric current from the alternator to thefirst inverter via the primary bus is concurrently supplied with theelectric current from the turbocharger assist device to the secondinverter via the secondary bus.
 16. The method of claim 14, wherein thefirst and second inverters are disposed onboard a vehicle and the firstand second loads are first and second traction motors, respectively, themethod further comprising: controlling the first and second tractionmotors to generate tractive effort to propel movement of the vehicle,the tractive effort generated based on the electric current suppliedfrom the alternator through the first inverter to the first tractionmotor and the electric current supplied from the turbocharger assistdevice through the second inverter to the second traction motor.
 17. Themethod of claim 16, wherein the electric current is supplied from theturbocharger assist device to the second inverter for powering thesecond traction motor in a generator mode, and the method furthercomprises: supplying, responsive to switching to a motor mode, electriccurrent generated by the second traction motor from the second inverterto the turbocharger assist device via the secondary bus for theturbocharger assist device to convert the electric current intomechanical energy for rotating the rotor of the turbocharger.
 18. Themethod of claim 14, further comprising monitoring, via one or moreprocessors, an operating parameter of one or more of the engine or theturbocharger, and wherein the electric current is supplied from theturbocharger assist device to the second inverter for powering thesecond load responsive to the operating parameter being greater than adesignated threshold.
 19. The method of claim 14, further comprisingmonitoring, via one or more processors, an operating parameter of one ormore of the engine or the turbocharger, and blocking the turbochargerassist device from supplying electric current to the second inverter viathe secondary bus responsive to the operating parameter being below adesignated threshold.
 20. A vehicle propulsion system comprising: analternator configured to be disposed onboard a vehicle and to generateelectric current based on mechanical energy received from an engine; aturbocharger operably coupled to the engine; a turbocharger assistdevice mechanically connected to the turbocharger and configured togenerate electric current based on rotation of a rotor of theturbocharger; first and second traction motors mechanically connected tofirst and second wheelsets, respectively, each of the first and secondwheelsets including at least two wheels, the first traction motorelectrically isolated from the second traction motor; a first inverterelectrically connected to the first traction motor and to the alternatorvia a primary bus, the first inverter configured to receive the electriccurrent generated by the alternator to power the first traction motor torotate the wheels of the first wheelset for propelling movement of thevehicle; and a second inverter electrically connected to the secondtraction motor and to the turbocharger assist device via a secondarybus, the second inverter configured to receive the electric currentgenerated by the turbocharger assist device to power the second tractionmotor to rotate the wheels of the second wheelset for propelling themovement of the vehicle.